There have been discussed noise suppressing apparatuses like an active noise controller which suppresses a noise by generating such sounds that it cancels out the noise when the noise occurs (for example, refer to Japanese Laid-Open Patent Publication No. 2001-057699, Japanese Laid-Open Patent Publication No. 1991(H03)-044299, and Japanese Laid-Open Patent Publication No. 1993(H05)-011771). FIG. 19 is a schematic view of a configuration example of a noise suppressing apparatus of related art. Incidentally, FIG. 19 shows a view in which the noise suppressing apparatus and a listener are viewed from above, and the listener faces towards the upper part of FIG. 19.
The noise suppressing apparatus illustrated in FIG. 19 includes a noise source 101, a loud speaker to output a canceling sound for canceling out the noise, an error microphone 103 provided in the vicinity of the listener, a reference microphone 104 to receive the sound (noise) from the noise source 101 and convert it to a tone signal, a canceling sound generating module 105 and the like.
The noise suppressing apparatus of the configuration described above finds transfer functions of sound (noise) between the noise source 101 and the error microphone 103 in the canceling sound generating module 105 on the basis of the tone signals received by the reference microphone 104 and the tone signals received by the error microphone 103. The noise suppressing apparatus also generates the canceling sound such that the sound (noise) received by the error microphone 103 is made into a minimum on the basis of the transfer functions found in the canceling sound generating module 105, and outputs the canceling sound generated from the loud speaker 102.